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400 BCE
Democritus
Democritus was an ancient Greek philosopher/scientist. He used reasoning as opposed to science when coming up with his theory on the atom which included the following: -Everything is composed of "atoms", which are physically, but not geometrically, indivisible. -Between Atoms, there lies empty space. -Atoms are indestructible. -Atoms always have been and always will be in motion. -There are an infinite number of atoms, and an infinite kinds of atoms, which differ in shape, and size. -
Isaac Newton
(1642-1727) Isaac Newton was an English physicist and mathematician and was responsible for Newton's Three Laws of Motion and Newton's Law of Universal Gravitation. He was also the first to propose a Mechanical Universe with small, solid masses in motion. -
Antoine- Laurent Lavoisier
(1743-1794) Antoine-Laurent Lavoisier was a prominent French chemist and was a leading figure in the 18th-century chemical revolution. He also created the Law of Conservation of Mass which states "Matter cannot be created nor destroyed, only rearranged." He was also the first to prove that although matter's shape may change.It's mass will remain the same. -
Julius Plücker
(1801-1868) Julius Plücker was a German mathematician and physicist and built one of the first cathode-ray tubes and in doing so paved the way for people that came after him. He was also professor of physics at the University of Bonn for a few years before beginning his work that he is known for. -
Dmitri Mendeleev
(1834-1907) Dmitri Mendeleev was a Russian chemist who is credited with the creation of the periodic table. But when he arranged all the elements in order from lightest to heaviest atomic weight he also left gaps in places where he believed unknown elements would find their place and even predicted their properties and years later some of those elements were discovered. -
J.J Thomson
(1856-1940) J.J Thomson was an English physicist and Nobel Laureate in Physics. It was obvious from early on that Thomson was interested in the atomic structure because in 1884 he wrote "Treatise on the Motion of Vortex Rings" which won him the 1884 Adams Prize. He also did a lot of research into cathode rays which led to the discovery of the Electron in 1897. -
Frederick Soddy
(1877-1956) Frederick Soddy was an English chemist and is recognized for elaborating on the theory "isotope" to explain the "unintentional breakdown of radioactive elements". He also received the 1921 Nobel Prize for his work and also spent time working with Rutherford. Lastly, he was one of the first to find out that certain elements might exist in forms that have different atomic weights while being indistinguishable and inseparable chemically. -
Ernest Rutherford
(1871-1937)Ernest Rutherford was a New-Zealand born physicist who was responsible for the discovery of the Nucleus in 1911 when he did an experiment called the GoldFoilExperiment in which he discovered that the atom must have a concentrated positive center charge that contains most of the atom's mass which later became known as the nucleus. After discovering the Nucleus Ernest Rutherford suggested that the it contained a particle with a positive charge, it became known as the Proton in 1920. -
Niels Bohr
(1885-1962) Niels Bohr was a Danish physicist who was generally regarded as the first to apply the quantum concept to the problem of atomic and molecular structure. But he also proposed an atomic structure theory that stated "the outer orbit of an atom could hold more electrons than the inner orbit". That's why he is highly regarded and part of the atomic structure's history. -
James Chadwick
(1891-1974) James Chadwick was an English Physicist who won the 1935 Nobel Prize for Physics. He was also responsible for discovering the Neutron in 1932
